Calcitonin Gene-Related Peptide Modulators - The History and Renaissance of a New Migraine Drug Class

Efficacy and safety of fremanezumab in patients with episodic and chronic migraine with documented inadequate response to 2 to 4 classes of migraine preventive medications over 6 months of treatment in the phase 3b FOCUS study

Background

Fremanezumab, a fully humanized monoclonal antibody (IgG2Δa) selectively targets the calcitonin gene-related peptide and has proven efficacy for the preventive treatment of migraine. In this study, we evaluated the long-term efficacy, safety, and tolerability of monthly and quarterly fremanezumab.

Methods

Episodic migraine and chronic migraine patients completing the 12-week double-blind period of the FOCUS trial entered the 12-week open-label extension and received 3 monthly doses of fremanezumab (225 mg). Changes from baseline in monthly migraine days, monthly headache days of at least moderate severity, days of acute headache medication use, days with photophobia/phonophobia, days with nausea or vomiting, disability scores, and proportion of patients achieving a ≥50% or  ≥75% reduction in monthly migraine days were evaluated.

Results

Of the 807 patients who completed the 12-week double-blind treatment period and entered the open-label extension, 772 patients completed the study. In the placebo, quarterly fremanezumab, and monthly fremanezumab dosing regimens, respectively, patients had fewer average monthly migraine days (mean [standard deviation] change from baseline: − 4.7 [5.4]; − 5.1 [4.7]; − 5.5 [5.0]), monthly headache days of at least moderate severity (− 4.5 [5.0]; − 4.8 [4.5]; − 5.2 [4.9]), days per month of acute headache medication use (− 4.3 [5.2]; − 4.9 [4.6]; − 4.8 [4.9]), days with photophobia/phonophobia (− 3.1 [5.3]; − 3.4 [5.3]; − 4.0 [5.2]), and days with nausea or vomiting (− 2.3 [4.6]; − 3.1 [4.5]; − 3.0 [4.4]). During the 12-week open-label extension, 38%, 45%, and 46% of patients, respectively, achieved a ≥50% reduction and 16%, 15%, and 20%, respectively, achieved a ≥75% reduction in monthly migraine days. Disability scores were substantially improved in all 3 treatment groups. There were low rates of adverse events leading to discontinuation (<1%).

Conclusion

Fremanezumab demonstrated sustained efficacy up to 6 months and was well tolerated in patients with episodic migraine or chronic migraine and documented inadequate response to multiple migraine preventive medication classes.

Trial registration

ClinicalTrials.gov NCT03308968 (FOCUS).

A narrative review of the importance of pharmacokinetics and drug-drug interactions of preventive therapies in migraine management

Objective

To review the pharmacokinetics of major classes of migraine preventives and the clinical implications of drug–drug interactions (DDIs) with the use of these therapies in migraine management.

Background

Preventive treatments for migraine are recommended for a large proportion of patients with frequent migraine attacks. These patients often exhibit a number of comorbidities, which may lead to the introduction of multiple concomitant therapies. Potential DDIs must be considered when using polytherapy to avoid increased risk of adverse events (AEs) or inadequate treatment of comorbid conditions.

Methods

A literature search was performed to identify pharmacokinetic properties and potential DDIs of beta‐blockers, antiepileptic drugs, antidepressants, calcium channel blockers, gepants, and monoclonal antibody therapies targeting the calcitonin gene‐related peptide pathway with medications that may be used for comorbid conditions.

Results

Most DDIs occur through alterations in cytochrome P450 isoenzyme activity and may be complicated by genetic polymorphism for metabolic enzymes. Additionally, drug metabolism may be altered by grapefruit juice ingestion and smoking. The use of migraine preventive therapies may exacerbate symptoms of comorbid conditions or increase the risk of AEs associated with comorbid conditions as a result of DDIs.

Conclusions

DDIs are important to consider in patients with migraine who use multiple medications. The development of migraine‐specific evidence‐based preventive treatments allows for tailored clinical management that reduces the risk of DDIs and associated AEs in patients with comorbidities.

Clinical features, disease progression, and use of healthcare resources in a large sample of 866 patients from 24 headache centers: A real-life perspective from the Italian chROnic migraiNe (IRON) project

OBJECTIVE

To develop a dedicated Italian chronic migraine (CM) database (IRON project) to overcome disease misconceptions, improve clinical administration, reduce patients' burden, and rationalize economic resource allotment.

BACKGROUND

Proper CM management requires a comprehensive appraisal of its full clinical, social, and economic complexity.

METHODS

In this cross-sectional study, CM patients were screened in 24 certified headache centers with face-to-face interviews. Information on sociodemographic factors, medical history, characteristics of CM, and of prior episodic migraine (EM), and healthcare resource use was gathered using a semistructured web-based questionnaire.

RESULTS

A total of 866 CM patients were enrolled. CM started ~20 years after EM onset (age at EM onset 17.4 ± 9.1 vs. age at CM onset 35.3 ± 12.5 [mean ± SD]). CM prophylaxis, used by 430/866 (49.6%) of the patients, was often ineffective, not tolerated, and prematurely discontinued. Medications and diagnostic workup, frequently inappropriate, were mostly subsidized by the Italian national health service. CM patients with ≥25 headache days/month revealed substantial clinical differences and heavier disability and economic burden compared with those with <25 headache days/month.

CONCLUSIONS

CM is a heterogeneous headache disorder deserving more in-depth clinical characterization, sharper diagnostic criteria, and tailored treatments. CM registries are expected to improve clinical management, resulting in increased disease awareness, better healthcare resource allocation, and reduced economic burden.

CGRP receptor antagonists for migraine. Are they also AMY1 receptor antagonists?

The development of several drugs that target the calcitonin gene-related peptide (CGRP) system has been a major breakthrough in the pharmacological management of migraine. These are divided into two major classes, antibodies which bind to the CGRP peptide, preventing it from activating CGRP receptors and receptor antagonists. Within the receptor antagonist class, there are two mechanisms of action, small molecule receptor antagonists and an antibody antagonist. This mini-review considers the pharmacology of these receptor targeted antagonist drugs at the CGRP receptor and closely related AMY₁ receptor, at which CGRP may also act. The antagonists are most potent at the CGRP receptor but can also show antagonism of the AMY₁ receptor. However, important data are missing and selectivity parameters cannot be provided for all antagonists. The clinical implications of AMY₁ receptor antagonism are unknown, but we urge consideration of this receptor as a potential contributing factor to CGRP and antagonist drug actions.

Novel Therapies in Acute Migraine Management: Small-Molecule Calcitonin Gene-Receptor Antagonists and Serotonin 1F Receptor Agonist

OBJECTIVE

To review the efficacy, safety, and cost of 3 newly approved agents-ubrogepant, lasmiditan, and rimegepant-representing 2 therapeutic classes, calcitonin gene-related peptide (CGRP) receptor antagonist and serotonin 1F (5-HT1F) agonists, for the acute treatment of migraine with or without aura.

DATA SOURCES

The Institute of Health US National Library of Medicine Clinical Trials, PubMed, and Cochrane databases were queried. Abstracts, journal articles, and other relevant sources published or present were reviewed. Search terms included the following: ubrogepant, MK-1602, Ubrelvy®, rimegepant, Nurtec®, BHV-3000, BMS-927711, lasmiditan, Reyvow®, LY573144.

STUDY SELECTION AND DATA EXTRACTION

Relevant English-language articles from June 30, 2010, to August 31, 2020, were evaluated and included in the narrative.

DATA SYNTHESIS

CGRP receptor antagonists, ubrogepant and rimegepant, achieved 2-hour pain freedom and freedom from the most bothersome migraine symptom (MBS) at 2 hours. Both agents were well tolerated, with adverse effects similar to placebo. Lasmiditan, a 5-HT1F receptor antagonist, also improved 2-hour pain freedom and freedom from the MBS at 2 hours. Lasmiditan is associated with dizziness, paresthesia, somnolence, nausea, fatigue, and lethargy.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Ubrogepant, rimegepant, and lasmiditan represent a new and exciting chapter in acute migraine therapy. To date, no head-to-head studies have compared these agents with the triptans. Ubrogepant and lasmiditan are effective in triptan nonresponders. None of the 3 agents is contraindicated in cardiovascular disease, unlike the triptans.

CONCLUSIONS

Based on available data, ubrogepant, rimegepant, and lasmiditan should be reserved as second-line therapy and may be safe in patients with cardiovascular risk. Lasmiditan's adverse effect profile may limit its use.

Zolmitriptan Intranasal Spanlastics for Enhanced Migraine Treatment; Formulation Parameters Optimized via Quality by Design Approach

Zolmitriptan is a potent second-generation triptan prescribed for migraine attacks. It suffers low bioavailability (40%) after oral administration due to the hepatic first-pass metabolism. Spanlastics are surfactant-based elastic vesicular drug carrier systems. This study aimed to design and optimize intranasal spanlastic formulations as an alternative approach that directly targets brain delivery, enhancing its bioavailability and avoiding the first-pass effect. The quality by design approach was applied to correlate the formulation parameters (Span 60 and Tween 80 concentrations) and critical quality attributes (entrapment efficiency (EE%) and particle size). Spanlastic formulations were designed based on response surface central composite design and prepared via an ethanol injection method. Designed formulations were characterized by EE% and particle size measurements to select the optimized formula (with a combination of small particle size and high EE%). The optimized formula was further subjected to transmission electron microscopy, zeta potential measurement and ex vivo permeation study. The optimized formulation showed a particle size of 117.5 nm and EE% of 45.65%, with a low percentage of error between the observed and predicted values. Seventy percent of zolmitriptan was permeated through the nasal membrane within 30 min, and it completely permeated within 2 h with a significantly higher steady-state flux compared to plain gel. This study introduced a successful and promising intranasal formulation suitable for further brain delivery analysis.

Efficacy of erenumab in chronic migraine patients with and without ictal allodynia

BACKGROUND

Ictal cutaneous allodynia, common in chronic migraine, is associated with reduced responses to acute treatment with triptans. Allodynia's impact on the efficacy of newer preventive treatments such as erenumab is unknown.

METHODS

Post-hoc subgroup analysis of a double-blind, randomized, placebo-controlled 12-week study of erenumab in chronic migraine, contrasting those with no allodynia with those with moderate-severe allodynia assessed with the Allodynia Symptom Checklist-12, was undertaken.

RESULTS

Of 648 randomized individuals with baseline Allodynia Symptom Checklist-12 scores, 386 (59.6%) had no allodynia and 153 (23.6%) had moderate-to-severe allodynia. Mean (standard deviation) baseline monthly migraine days were 17.6 (4.8) and 18.9 (4.3), respectively. Compared to placebo, the erenumab group had greater reductions in monthly migraine days and monthly acute migraine-specific medication days in both no allodynia and allodynia subgroups. Mean (95% confidence interval) treatment differences in change from baseline for monthly migraine days at week 12 were -2.5 (-3.7, -1.4) in the no allodynia subgroup and -3.3 (-5.3, -1.3) in the moderate-severe allodynia subgroup. Change in acute migraine-specific medication days were -3.3 (-4.3, -2.3) and -2.5 (-4.3, -0.8), respectively.

CONCLUSIONS

Erenumab's efficacy in reducing monthly migraine days and acute migraine-specific medication days in chronic migraine was not impacted by the presence of moderate-severe ictal allodynia.Trial registration: ClinicalTrials.gov NCT02066415.

Calcitonin gene-related peptide (CGRP) receptor antagonists: Heterocyclic modification of a novel azepinone lead

In our efforts to identify orally bioavailable CGRP receptor antagonists, we previously discovered a novel series of orally available azepinone derivatives that unfortunately also exhibited the unwanted property of potent time-dependent human CYP3A4 inhibition. Through heterocyclic replacement of the indazole ring, we discovered a series of heterocycle derivatives as high-affinity CGRP receptor antagonists. Some of them showed reasonable oral exposures, and the imidazolone derivatives that showed good oral exposure also exhibited substantially reduced time-dependent CYP3A4 inhibition. Several compounds showed strong in vivo efficacy in our marmoset facial blood flow assay with up to 87% inhibition of CGRP-induced activity. However, oral bioavailability generally remained low, emphasizing the challenges we and others encountered in discovering clinical development candidates for this difficult Class B GPCR target.

CGRP Receptor Antagonists and 5-HT1F Receptor Agonist in the Treatment of Migraine

Discovering that calcitonin-related peptide (CGRP) plays a key role in the complex pathophysiology of migraine has allowed us to make great strides in the development of new approaches for acute and preventive treatment. This evidence has led to the development of small molecules antagonist molecules of the CGRP receptor ("gepants") and of a new class of medications called "Ditans". This review presents the data from clinical trials reporting the efficacy, safety, and tolerability of the new drugs used in the treatment of migraines. Evidences show that therapeutic approaches targeted to CGRP have the potential to transform the clinical management of migraine, even though its appropriate place has yet to be determined with accuracy.

Single-Dose Pharmacokinetics and Safety of Atogepant in Adults With Hepatic Impairment: Results From an Open-Label, Phase 1 Trial

Atogepant is a selective oral calcitonin gene‐related peptide receptor antagonist in development for migraine prevention. Here, we report the pharmacokinetics (PK) and safety of single‐dose 60 mg atogepant in participants with severe, moderate, or mild hepatic impairment and matched participants with normal hepatic function from an open‐label, parallel‐group, single‐dose phase 1 trial. Thirty‐two participants aged 45 to 72 years were enrolled, which included 8 each with severe, moderate, mild, or no hepatic impairment. All participants completed the study. Atogepant was rapidly absorbed (median time to maximum plasma concentration, ∼2 hours) with an apparent terminal elimination half‐life of ∼11 hours. Compared with participants with normal hepatic function, the change in maximum plasma concentrations of atogepant were –4%, –12%, and +9% in participants with severe, moderate, or mild hepatic impairment, respectively. Overall systemic exposures to atogepant were 15% to 38% higher in participants with hepatic impairment compared with those with normal hepatic function, but these differences are not expected to be clinically relevant given the established safety profile of atogepant. Only 1 adverse event was reported: mild rhinorrhea in a participant with moderate hepatic impairment. Overall, atogepant was safe and not associated with any clinically relevant change in PK in participants with severe, moderate, or mild hepatic impairment.

Erenumab in the prevention of high-frequency episodic and chronic migraine: Erenumab in Real Life in Italy (EARLY), the first Italian multicenter, prospective real-life study

OBJECTIVE

To assess the effectiveness, safety, and tolerability of erenumab in a real-life migraine population, while trying to identify responsiveness predictors.

BACKGROUND

Erenumab is a fully human Ig-2 monoclonal antibody blocking the calcitonin gene-related peptide receptor, indicated for migraine prophylaxis. Phase II and III trials demonstrated that erenumab is effective, safe, and well tolerated in the prevention of episodic and chronic migraine (CM), showing an early onset of action.

METHODS

This is a multicenter, prospective, cohort, and real-life study. We considered for enrolment all consecutive patients aged 18-65 affected by high-frequency episodic migraine (HFEM) or CM, with or without medication overuse, visited at nine Italian Headache Centers from December 20, 2018 to September 30, 2019. Each patient was treated with erenumab 70 mg, administered subcutaneously every 4 weeks. Treatment duration was planned to last from 6 to 12 months, depending on the patient's response. The primary endpoint was the change in monthly migraine days (MMDs) at weeks 9-12 compared to baseline. Secondary endpoints included changes in monthly analgesics intake, ≥50%, ≥75%, and 100% responder rates and any variation in the Visual Analog Scale (VAS) and Headache Impact Test scores (HIT).

RESULTS

In total, 372 migraine patients were treated with at least one dose of erenumab 70 mg. At weeks 9-12, erenumab decreased MMDs by 4.5 ± 4.1 days (mean ± SD) in patients with HFEM and by 9.3 ± 9.1 (mean ± SD) days in those with CM compared to baseline. At weeks 9-12 VAS score was reduced by 1.9 ± 1.9 (mean ± SD), HIT score by 10.7 ± 8.8 (mean ± SD), and median monthly analgesics intake passed from 12.0 (interquartile range [IQR] 10.0-14.0) to 5.0 (IQR 3.0-7.0) in HFEM. In CM patients, VAS was reduced by 1.7 ± 2.0 (mean ± SD), HIT by 9.7 ± 10.4 (mean ± SD), and median monthly analgesics intake passed from 20.0 (IQR 15.0-30.0) to 8.0 (IQR 5.0-15.0). At week 12, ≥50% responders were 60/101 (59.4%) for HFEM and 146/263 (55.5%) for CM, ≥75% responders were 17/101 (16.8%) and 59/263 (22.4%) and 100% responders 1/101 (1.0%) and 3/263 (1.1%), respectively. Erenumab responsiveness in HFEM was positively associated with unilateral pain localization (OR: 3.03, 95% CI: 1.24-7.40; p = 0.015), whereas in CM responsiveness was positively associated with and baseline migraine frequency (OR: 1.06, 95% CI:1.02-1.11; p = 0.031), dopaminergic symptoms (OR: 2.01, 95% CI: 1.14-3.52; p = 0.015), and negatively associated with psychiatric comorbidities (OR: 0.43, 95% CI: 0.20-0.93; p = 0.003).

CONCLUSIONS

Erenumab 70 mg is effective, safe, and well tolerated in real life. Easily obtainable clinical features might be of help in predicting patient's responsiveness.

A phase 2, randomized, double-blind, placebo-controlled trial of AMG 301, a pituitary adenylate cyclase-activating polypeptide PAC1 receptor monoclonal antibody for migraine prevention

Objective

To assess the safety and efficacy of AMG 301, an inhibitor of the pituitary adenylate cyclase-activating polypeptide (PACAP)-1 (PAC1) receptor, for prevention of migraine.

Methods

In a double-blind trial, patients were randomized 4:3:3 to placebo, AMG 301 210 mg every 4 weeks, or AMG 301 420 mg every 2 weeks for 12 weeks. Effect on monthly migraine days and other secondary measures were assessed over weeks 9–12. Safety and tolerability were assessed.

Results

Of 343 randomized patients (mean age, 41.8–42.5 years), the majority were women (85.4–90.4%), white (94.1–96.2%), and had episodic migraine (62.5–67.9%). A total of 305 patients completed treatment (placebo, n = 124; AMG 301 210 mg, n = 94; AMG 301 420 mg, n = 87). Least squares mean reduction at week 12 in monthly migraine days from baseline was −2.5 (0.4) days for placebo and −2.2 (0.5) days for both AMG 301 treatment groups. No difference between AMG 301 and placebo on any measure of efficacy was observed; mean (95% confidence interval) treatment difference versus placebo for monthly migraine days for AMG 301 210 mg, 0.3 (−0.9 to 1.4); AMG 301 420 mg, 0.3 (−0.9 to 1.4). The incidence of adverse events was similar across groups.

Conclusion

AMG 301 offered no benefit over placebo for migraine prevention; further studies may be necessary to fully understand the role of PACAP isoforms and its receptors in migraine pathophysiology.

Study Registration

ClinicalTrials.gov: NCT03238781

Combined onabotulinumtoxinA/atogepant treatment blocks activation/sensitization of high-threshold and wide-dynamic range neurons

Background

OnabotulinumtoxinA and agents that block calcitonin gene‒receptor peptide action have both been found to have anti-migraine effects, but they inhibit different populations of meningeal nociceptors. We therefore tested the effects of combined treatment with onabotulinumtoxinA and the calcitonin gene‒receptor peptide antagonist atogepant on activation/sensitization of trigeminovascular neurons by cortical spreading depression.

Material and methods

Single-unit recordings were obtained of high-threshold and wide-dynamic-range neurons in the spinal trigeminal nucleus, and cortical spreading depression was then induced in anesthetized rats that had received scalp injections of onabotulinumtoxinA 7 days earlier and intravenous atogepant infusion 1 h earlier. The control group received scalp saline injections and intravenous vehicle infusion.

Results

OnabotulinumtoxinA/atogepant pretreatment prevented cortical spreading depression-induced activation and sensitization in both populations (control: Activation in 80% of high-threshold and 70% of wide-dynamic-range neurons, sensitization in 80% of high-threshold and 60% of wide-dynamic-range neurons; treatment: activation in 10% of high-threshold and 0% of wide-dynamic-range neurons, sensitization in 0% of high-threshold and 5% of wide-dynamic-range neurons).

Discussion

We propose that the robust inhibition of high-threshold and wide-dynamic-range neurons by the combination treatment was achieved through dual blockade of the Aδ and C classes of meningeal nociceptors. Combination therapy that inhibits meningeal C-fibers and prevents calcitonin gene‒receptor peptide from activating its receptors on Aδ-meningeal nociceptors may be more effective than a monotherapy in reducing migraine days per month in patients with chronic migraine.

Atogepant Is Not Associated With Clinically Meaningful Alanine Aminotransferase Elevations in Healthy Adults

Atogepant is a potent, selective, oral calcitonin gene–related peptide (CGRP) receptor antagonist in development for migraine prevention. The chemical structure of atogepant is distinct from previous CGRP receptor antagonists, which were associated with elevated serum alanine aminotransferase (ALT) in clinical trials. Here, we report the safety, tolerability, and pharmacokinetics (PKs) of a once‐daily supratherapeutic dose (170 mg) of atogepant for 28 days from a randomized, double‐blind, placebo‐controlled phase I trial in healthy participants. Overall safety, hepatic safety, and plasma PK parameters were evaluated. Thirty‐four participants aged 23–55 years enrolled; 28 (82.4%) completed the study in accordance with the protocol. Multiple doses of 170 mg atogepant for 28 consecutive days were generally well‐tolerated. All adverse events (AEs; reported in 87.0% of the atogepant group; 72.7%, placebo) were mild in severity except one serious AE of subarachnoid hemorrhage due to a bicycle accident and not considered related to treatment. There were two discontinuations due to AEs, both with atogepant, one considered possibly related to treatment. Over 28 days of treatment, no participant receiving atogepant had an ALT elevation above 1.5 × upper limit of normal. Change from baseline in serum ALT levels was not different between atogepant and placebo. Atogepant is rapidly absorbed (median time to maximum plasma concentration, ~ 2 hours) with an apparent terminal half‐life of ~ 11 hours, and no evidence of accumulation after once‐daily dosing. Overall, atogepant at a high oral dose is safe and well‐tolerated in healthy participants with no clinically meaningful elevations in ALT.

Identifying Outcome Measures for Migraine Value-Based Contracting Using the Delphi Method

OBJECTIVE

To identify meaningful migraine outcome measures among key stakeholders to inform value-based contracts for migraine medications.

BACKGROUND

Value-based contracts linking medication payments to predefined performance metrics aim to promote value through aligned incentives and shared risk between manufacturers and payers. The emergence of new and expensive pharmaceuticals for migraine presents an opportunity for value-based contract development. However, uncertainty remains around which outcomes are most meaningful to all migraine stakeholders.

METHODS

This study utilized a Delphi survey to incorporate views from 82 stakeholders, including patients (n = 21), providers (n = 23), payers (n = 10), employers (n = 18), and pharmaceutical company representatives (n = 10). A list of 15 migraine-related outcomes was created from a literature review and subject matter expert consultation. Stakeholders reported on the value of these outcomes through a 5-point Likert scale and selection of their top 3 most meaningful outcomes. All participants except patients and employers also used a 5-point Likert scale to rate the feasibility of collecting each outcome measure. Consensus was defined as ≥75% agreement on the importance and feasibility of an outcome (Likert scores ≥4/5 or selection of an outcome as most meaningful).

RESULTS

After 2 rounds, consensus was achieved for importance of 9 outcomes on the Likert scale. "Decrease in migraine frequency" reached 100% agreement (82/82), followed by "increased ability to resume normal activities" (96%, 79/82). When asked to choose the 3 most meaningful outcomes, stakeholders selected "decrease in migraine frequency" (88%, 72/82) followed by "decrease in migraine severity" (80%, 66/82). The 2 measures rated as most feasibly collected were "decrease in emergency department/urgent care visits" (95%, 40/42) and "decrease in migraine frequency" (90%, 38/42). There were statistically significant differences between non-patient and patient stakeholders in selection of "decrease in emergency department/urgent care visits" [20% (12/61) vs 0% (0/21), P = .031]; and employer and patient stakeholders in selection of "decrease in work days missed" [44% (8/18) vs 5% (1/21), P = .006] and "decrease in emergency department/urgent care visits" [22% (4/18) vs 0% (0/21), P = .037] as most meaningful outcomes.

CONCLUSIONS

The measures "decrease in migraine frequency" followed by "decrease in migraine severity" were identified as top priority migraine outcome measures.

Mechanistic Investigations Support Liver Safety of Ubrogepant

Small-molecule calcitonin gene-related peptide (CGRP) receptor antagonists have demonstrated therapeutic efficacy for the treatment of migraine. However, previously investigated CGRP receptor antagonists, telcagepant and MK-3207, were discontinued during clinical development because of concerns about drug-induced liver injury. A subsequent effort to identify novel CGRP receptor antagonists less likely to cause hepatotoxicity led to the development of ubrogepant. The selection of ubrogepant, following a series of mechanistic studies conducted with MK-3207 and telcagepant, was focused on key structural modifications suggesting that ubrogepant was less prone to forming reactive metabolites than previous compounds. The potential for each drug to cause liver toxicity was subsequently assessed using a quantitative systems toxicology approach (DILIsym) that incorporates quantitative assessments of mitochondrial dysfunction, disruption of bile acid homeostasis, and oxidative stress, along with estimates of dose-dependent drug exposure to and within liver cells. DILIsym successfully modeled liver toxicity for telcagepant and MK-3207 at the dosing regimens used in clinical trials. In contrast, DILIsym predicted no hepatotoxicity during treatment with ubrogepant, even at daily doses up to 1000 mg (10-fold higher than the approved clinical dose of 100 mg). These predictions are consistent with clinical trial experience showing that ubrogepant has lower potential to cause hepatotoxicity than has been observed with telcagepant and MK-3207.

Application of a Rat Liver Drug Bioactivation Transcriptional Response Assay Early in Drug Development That Informs Chemically Reactive Metabolite Formation and Potential for Drug-induced Liver Injury

Drug-induced liver injury is a major reason for drug candidate attrition from development, denied commercialization, market withdrawal, and restricted prescribing of pharmaceuticals. The metabolic bioactivation of drugs to chemically reactive metabolites (CRMs) contribute to liver-associated adverse drug reactions in humans that often goes undetected in conventional animal toxicology studies. A challenge for pharmaceutical drug discovery has been reliably selecting drug candidates with a low liability of forming CRM and reduced drug-induced liver injury potential, at projected therapeutic doses, without falsely restricting the development of safe drugs. We have developed an in vivo rat liver transcriptional signature biomarker reflecting the cellular response to drug bioactivation. Measurement of transcriptional activation of integrated nuclear factor erythroid 2-related factor 2 (NRF2)/Kelch-like ECH-associated protein 1 (KEAP1) electrophilic stress, and nuclear factor erythroid 2-related factor 1 (NRF1) proteasomal endoplasmic reticulum (ER) stress responses, is described for discerning estimated clinical doses of drugs with potential for bioactivation-mediated hepatotoxicity. The approach was established using well benchmarked CRM forming test agents from our company. This was subsequently tested using curated lists of commercial drugs and internal compounds, anchored in the clinical experience with human hepatotoxicity, while agnostic to mechanism. Based on results with 116 compounds in short-term rat studies, with consideration of the maximum recommended daily clinical dose, this CRM mechanism-based approach yielded 32% sensitivity and 92% specificity for discriminating safe from hepatotoxic drugs. The approach adds new information for guiding early candidate selection and informs structure activity relationships (SAR) thus enabling lead optimization and mechanistic problem solving. Additional refinement of the model is ongoing. Case examples are provided describing the strengths and limitations of the approach.

Antagonism of CGRP Signaling by Rimegepant at Two Receptors

The “gepants” are a class of calcitonin gene-related peptide (CGRP) receptor antagonist molecules that have been developed for the prevention and treatment of migraine. Rimegepant is reported to act at the CGRP receptor, has good oral bioavailability, and has had positive clinical trial results. However, there is very little data available describing its receptor pharmacology. Importantly, rimegepant activity at the AMY₁ receptor, a second potent CGRP receptor that is known to be expressed in the trigeminovascular system, has not been reported. The ability of rimegepant to antagonize activation of human CGRP, AMY₁, and related adrenomedullin receptors was determined in transfected in Cos7 cells. Rimegepant was an effective antagonist at both the CGRP and AMY₁ receptor. The antagonism of both CGRP and AMY₁ receptors may have implications for our understanding of the mechanism of action of rimegepant in the treatment of migraine.

Anti-migraine Calcitonin Gene-Related Peptide Receptor Antagonists Worsen Cerebral Ischemic Outcome in Mice

Objective

Calcitonin gene–related peptide (CGRP) pathway inhibitors are emerging treatments for migraine. CGRP‐mediated vasodilation is, however, a critical rescue mechanism in ischemia. We, therefore, investigated whether gepants, small molecule CGRP receptor antagonists, worsen cerebral ischemia.

Methods

Middle cerebral artery was occluded for 12 to 60 minutes in mice. We compared infarct risk and volumes, collateral flow, and neurological deficits after pretreatment with olcegepant (single or 10 daily doses of 0.1–1mg/kg) or rimegepant (single doses of 10–100mg/kg) versus vehicle. We also determined their potency on CGRP‐induced relaxations in mouse and human vessels, in vitro.

Results

Olcegepant (1mg/kg, single dose) increased infarct risk after 12‐ to 20‐minute occlusions mimicking transient ischemic attacks (14/19 vs 6/18 with vehicle, relative risk = 2.21, p < 0.022), and doubled infarct volumes (p < 0.001) and worsened neurological deficits (median score = 9 vs 5 with vehicle, p = 0.008) after 60‐minute occlusion. Ten daily doses of 0.1 to 1mg/kg olcegepant yielded similar results. Rimegepant 10mg/kg increased infarct volumes by 60% after 20‐minute ischemia (p = 0.03); 100mg/kg caused 75% mortality after 60‐minute occlusion. In familial hemiplegic migraine type 1 mice, olcegepant 1mg/kg increased infarct size after 30‐minute occlusion (1.6‐fold, p = 0.017). Both gepants consistently diminished collateral flow and reduced reperfusion success. Olcegepant was 10‐fold more potent than rimegepant on CGRP‐induced relaxations in mouse aorta.

Interpretation

Gepants worsened ischemic stroke in mice via collateral dysfunction. CGRP pathway blockers might thus aggravate coincidental cerebral ischemic events. The cerebrovascular safety of these agents must therefore be better delineated, especially in patients at increased risk of ischemic events or on prophylactic CGRP inhibition. ANN NEUROL 2020;88:771–784

Early clinical experience with a monoclonal antibody against the calcitonin gene-related peptide receptor in adolescents with migraine: A case series

Management of migraine in adolescents poses a great challenge, as many of the approved pharmacological migraine preventive agents have age restrictions. Following favorable safety and efficacy reports of the new class agent calcitonin gene-related peptide (CGRP) monoclonal antibody for use in migraine prevention, there is growing interest in its application in pediatric migraine. We present here a case series detailing our experience of using erenumab, a CGRP monoclonal antibody, in six adolescent patients. Two patients had a reduction of at least 50% in the mean number of monthly migraine days, one patient reported subjective improvement, while three patients did not respond to the first dose of erenumab and discontinued treatment. One patient reported constipation associated with erenumab use. We speculate that CGRP monoclonal antibody could potentially be a viable option in adolescent patients with migraine. Further evidences that support efficacy and safety of erenumab in this group is needed.

Migraine Pathophysiology

Migraine is the leading cause of years lost due to disability in individuals aged 15 to 49 years. Much has changed over the last three decades about our understanding of this complex neurological disorder. Various phases of migraine have been characterized and are the focus of this review. The premonitory phase involves bothersome symptoms experienced hours to days before migraine pain. Behavioral changes and functional neuroimaging studies point toward hypothalamic involvement during the premonitory and other migraine phases. Migraine aura is a disruptive, reversible neurological phenomenon that affects up to one-third of all migraineurs, and can overlap with the headache phase. The mechanism responsible for this phase is thought to be cortical spreading depolarization through the cortex. This process leads to temporary disruptions in ion homeostasis and the ensuing neuronal dysfunction. The headache phase involves activation of the trigeminocervical complex. Neuropeptides are implicated in trigeminal activation, and calcitonin gene-related peptide in particular has become a promising target of therapeutic intervention for migraine. The final phase of migraine is the postdrome, the period of time from the resolution of headache symptoms until return to baseline following a migraine. People often report neuropsychiatric, sensory, gastrointestinal, and general symptoms during this time, which can limit activity. Elucidating the neuroanatomical, chemical, and neuroimaging correlates of these migraine phases allows for an improved comprehension of the underlying changes associated with migraine symptomatology and can assist with evaluation of arising therapeutics for migraine management.

ATP sensitive potassium (KATP) channel inhibition: A promising new drug target for migraine

BACKGROUND

Recently, the adenosine triphosphate (ATP) sensitive potassium channel opener levcromakalim was shown to induce migraine attacks with a far higher incidence than any previous provoking agent such as calcitonin gene-related peptide. Here, we show efficacy of ATP sensitive potassium channel inhibitors in two validated rodent models of migraine.

METHODS

In female spontaneous trigeminal allodynic rats, the sensitivity of the frontal region of the head was tested by an electronic von Frey filament device. In mice, cutaneous hypersensitivity was induced by repeated glyceryl trinitrate or levcromakalim injections over nine days, as measured with von Frey filaments in the hindpaw. Release of calcitonin gene-related peptide from dura mater and trigeminal ganglion was studied ex vivo.

RESULTS

The ATP sensitive potassium channel inhibitor glibenclamide attenuated the spontaneous cephalic hypersensitivity in spontaneous trigeminal allodynic rats and glyceryl trinitrate-induced hypersensitivity of the hindpaw in mice. It also inhibited CGRP release from dura mater and the trigeminal ganglion isolated from spontaneous trigeminal allodynic rats. The hypersensitivity was also diminished by the structurally different ATP sensitive potassium channel inhibitor gliquidone. Mice injected with the ATP sensitive potassium channel opener levcromakalim developed a progressive hypersensitivity that was completely blocked by glibenclamide, confirming target engagement.

CONCLUSION

The results suggest that ATP sensitive potassium channel inhibitors could be novel and highly effective drugs in the treatment of migraine.

Emerging Treatment Options for Migraine

Migraine is one of top 5 medical conditions that contribute to Years Lived with Disability and affects approximately 1 billion people from around the world. To date, preventive treatment and acute therapies for migraine are limited, have undesirable side effects and are poorly tolerated in patients. In the last few decades, considerable advances in our understanding of migraine and its pathophysiology have paved the way for the development of targeted treatment options. Calcitonin gene-related peptide (CGRP) plays an integral role in the neurobiology of migraine, and new classes of drugs that target the CGRP pathway have included gepants and CGRP pathway monoclonal antibodies. Serotonin 5-HT1F receptor agonists—namely ditans—have also been developed to treat acute migraine. Lastly, non-invasive neuromodulation offers another treatment option for migraine patients who prefer treatments that have fewer side effects and are well tolerated. In this review, we discussed emerging treatment options for migraine that were made available in recent years. Ann Acad Med Singapore 2020;49:226–35 Key words: Calcitonin gene-related peptide monoclonal antibody, Gepants, Headache, Lasmiditan, Neuromodulation

No central action of CGRP antagonising drugs in the GTN mouse model of migraine

Introduction

Clinically, calcitonin gene-related peptide antagonising drugs are recognized as effective in migraine treatment, but their site of action is debated. Only a small fraction of these compounds pass the blood-brain barrier and accesses the central nervous system. Regardless, it has been argued that the central nervous system is the site of action. Here, we test this hypothesis by bypassing the blood-brain barrier through intracerebroventricular injection of calcitonin gene-related peptide antagonising drugs.

Methods

We used the glyceryl trinitrate (GTN) mouse model, which is well validated by its response to specific migraine drugs. The calcitonin gene-related peptide receptor antagonist olcegepant and the calcitonin gene-related peptide monoclonal antibody ALD405 were administered either intraperitoneally or intracerebroventricularly. The outcome measure was cutaneous mechanical allodynia.

Results

Mice given olcegepant intraperitoneally + GTN on day 1 had a mean 50% withdrawal threshold of 1.2 g in contrast to mice receiving placebo + GTN, which had a threshold of 0.3 g ( p < 0.001). Similarly, in the ALD405 + GTN group, mice had thresholds of 1.2 g versus 0.2 g in the placebo + GTN group ( p < 0.001). However, both drugs were ineffective when delivered intracerebroventricularly, as control and active groups had identical mechanical sensitivity thresholds, 0.2 g versus 0.1 g and 0.1 g versus 0.1 g for olcegepant and ALD405, respectively ( p > 0.99 in both cases).

Discussion

The site of action of olcegepant and of the monoclonal antibody ALD405 is outside the blood-brain barrier in this mouse model of migraine. It is likely that these results can be generalised to all gepants and all antibodies and that the results are relevant for human migraine.

Looking Back at US Pharmacy’s Past to Help Discern Its Future

Objective: To review specific literature that aimed to predict the future of US pharmacy, beginning in the late 1980s. Data Sources: Articles were identified from searching MEDLINE, CINAHL, Google Scholar, and references of relevant articles. The following combinations of search terms were used: future, pharmacy, prediction, and forecast. Study Selection and Data Extraction: The following inclusion criteria were applied: (1) full-text commentary, review, or original research and (2) focused predominantly on the pharmacy in the United States. Data on predictions for the future of pharmacy were extracted. Data Synthesis: We selected 3 articles published between 1988 and 2006, with each aiming to project the future for the following decade. We examined each prediction in light of the current knowledge. Relevance to Patient Care and Clinical Practice: Educators, practitioners, and other stakeholders should consider reflecting on the changes in pharmacy for the past 3 decades and applying both historical and emerging trends to improve patient care and sustain practice in the third decade of the 21st century and beyond. Conclusion: Most of the predictions for the future of pharmacy from the past 3 decades materialized, with some still in progress (reimbursement for pharmacy services), whereas others manifested in unexpected ways (transition from shortage to excess of pharmacists). Current forces shaping pharmacy include, but are not limited to, growing spending and use of specialty drugs, automation of pharmacy operations, growth of pharmacy in the digital health enterprise, and growing consumer interest in the use of analytical pharmacy that tests drugs before dispensing.

Blocking the CGRP Pathway for Acute and Preventive Treatment of Migraine: The Evolution of Success

The pivotal role of calcitonin gene-related peptide (CGRP) in migraine pathophysiology was identified over 30 years ago, but the successful clinical development of targeted therapies has only recently been realized. This Perspective traces the decades long evolution of medicinal chemistry required to advance small molecule CGRP receptor antagonists, also called gepants, including the current clinical agents rimegepant, vazegepant, ubrogepant, and atogepant. Providing clinically effective blockade of CGRP signaling required surmounting multiple challenging hurdles, including defeating a sizable ligand with subnanomolar affinity for its receptor, designing antagonists with an extended confirmation and multiple pharmacophores while retaining solubility and oral bioavailability, and achieving circulating free plasma levels that provided near maximal CGRP receptor coverage. The clinical efficacy of oral and intranasal gepants and the injectable CGRP monoclonal antibodies (mAbs) are described, as are recent synthetic developments that have benefited from new structural biology data. The first oral gepant was recently approved and heralds a new era in the treatment of migraine.

The Emerging Role of Mechanosensitive Piezo Channels in Migraine Pain

Recently discovered mechanosensitive Piezo channels emerged as the main molecular detectors of mechanical forces. The functions of Piezo channels range from detection of touch and pain, to control of the plastic changes in different organs. Recent studies suggested the role of Piezo channels in migraine pain, which is supposed to originate from the trigeminovascular nociceptive system in meninges. Interestingly, migraine pain is associated with such phenomenon as mechanical hypersensitivity, suggesting enhanced mechanotransduction. In the current review, we present the data that propose the implication of Piezo channels in migraine pain, which has a distinctive pulsatile character. These data include: (i) distribution of Piezo channels in the key elements of the trigeminovascular nociceptive system; (ii) the prolonged functional activity of Piezo channels in meningeal afferents providing a mechanistical basis for mechanotransduction in nociceptive nerve terminals; (iii) potential activation of Piezo channels by shear stress and pulsating blood flow; and (iv) modulation of these channels by emerging chemical agonists and modulators, including pro-nociceptive compounds. Achievements in this quickly expanding field should open a new road for efficient control of Piezo-related diseases including migraine and chronic pain.

Ubrogepant Is Not Associated With Clinically Meaningful Elevations of Alanine Aminotransferase in Healthy Adult Males

Ubrogepant is a novel, oral calcitonin gene-related peptide (CGRP) receptor antagonist intended for the acute treatment of migraine attacks. Ubrogepant has a chemical structure distinct from previous small-molecule CGRP receptor antagonists that were associated with elevated serum alanine aminotransferase (ALT) in clinical trials. Here, we report overall and hepatic safety data from two placebo-controlled phase I trials of ubrogepant, spray-dried oral compressed tablet (SD-OCT) in healthy male volunteers. Trial A was a pharmacokinetic (PK) trial of single (100-400 mg) and multiple (40-400 mg) ascending doses. Trial B was a dedicated hepatic safety trial assessing daily use of ubrogepant 150 mg for 28 days. Serum ALT (as hepatotoxicity biomarker) and PK data are reported. Ubrogepant was well-tolerated in both trials, with a low incidence of adverse events that did not differ greatly from placebo. Changes in mean ALT levels were minimal and similar to placebo. Over 28 days of treatment, the mean percentage change in ALT from baseline was < 5% at all time points. No participant in either trial demonstrated ALT ≥ 3× upper limit of normal at any time. Ubrogepant SD-OCT demonstrated linear PK appropriate for acute treatment of migraine, with rapid uptake (time of maximum plasma concentration (t_max ): 2-3 hours) and no accumulation with daily use. Overall, there was no evidence of ubrogepant-associated hepatotoxicity with daily doses up to 400 mg for 10 days or with daily ubrogepant 150 mg for 28 days. Supratherapeutic dosing is a useful strategy for characterizing hepatic safety in early drug development.

Fluorescently-labeled fremanezumab is distributed to sensory and autonomic ganglia and the dura but not to the brain of rats with uncompromised blood brain barrier

Background

The presence of calcitonin gene-related peptide and its receptors in multiple brain areas and peripheral tissues previously implicated in migraine initiation and its many associated symptoms raises the possibility that humanized monoclonal anti-calcitonin gene-related peptide antibodies (CGRP-mAbs) can prevent migraine by modulating neuronal behavior inside and outside the brain. Critical to our ability to conduct a fair discussion over the mechanisms of action of CGRP-mAbs in migraine prevention is data generation that determines which of the many possible peripheral and central sites are accessible to these antibodies – a question raised frequently due to their large size.

Material and methods

Rats with uncompromised and compromised blood-brain barrier (BBB) were injected with Alexa Fluor 594-conjugated fremanezumab (Frema594), sacrificed 4 h or 7 d later, and relevant tissues were examined for the presence of Frema594.

Results

In rats with uncompromised BBB, Frema594 was similarly observed at 4 h and 7 d in the dura, dural blood vessels, trigeminal ganglion, C2 dorsal root ganglion, the parasympathetic sphenopalatine ganglion and the sympathetic superior cervical ganglion but not in the spinal trigeminal nucleus, thalamus, hypothalamus or cortex. In rats with compromised BBB, Frema594 was detected in the cortex (100 µm surrounding the compromised BBB site) 4 h but not 7 d after injections.

Discussion

Our inability to detect fluorescent (CGRP-mAbs) in the brain supports the conclusion that CGRP-mAbs prevent the headache phase of migraine by acting mostly, if not exclusively, outside the brain as the amount of CGRP-mAbs that enters the brain (if any) is too small to be physiologically meaningful.

Monoclonal antibodies for the prevention of migraine

Introduction: Calcitonin Gene-Related Peptide (CGRP) plays a crucial role in migraine pathophysiology. A novel specific treatment strategy for the prevention of migraine incorporates monoclonal antibodies (mAbs) against CGRP and its canonical receptor. Eptinezumab, fremanezumab and galcanezumab block CGRP mediated effects by binding to the peptide, while erenumab blocks the CGRP receptor.Areas covered: Following a brief overview of pharmacological characteristics, we will review phase III trials for the use of CGRP mAbs in the prevention of episodic and chronic migraine.Expert opinion: All four CGRP mAbs demonstrated an excellent safety, tolerability and efficacy profile in migraine patients. Across all trials mAbs showed superior efficacy for the reduction of monthly migraine days compared to placebo with a net benefit of 2.8 days. Neither cardiovascular nor immunological safety concerns have emerged from clinical trials. Fremanezumab, galcanezumab, and erenumab are approved in the USA and Europe. Based on trial data there is no reason why these mAbs should not become first-line therapies in future. For now, we advocate for the use of mAbs in migraine prevention for patients who failed a minimum of two standard oral treatments based on the novelty and costs of this approach. mAbs are also effective in patients with medication overuse and with comorbid depression or anxiety disorders. Taken together, mAbs are likely to usher in a new era in migraine prevention and provide significant value to patients.

From LBR-101 to Fremanezumab for Migraine

Calcitonin gene-related peptide (CGRP) is a neuropeptide of importance in migraine pathogenesis. Its central role in migraine was proven pharmacologically by the development of CGRP receptor antagonists. Monoclonal antibodies targeting CGRP or its receptor are effective in the preventive treatment of episodic and chronic migraine and are considered potential breakthroughs in their treatment. Fremanezumab (previously known as TEV-48125, LBR-101, or RN-307) is a humanized IgG2a monoclonal antibody that binds to CGRP. The development of this antibody validated the role of CGRP in chronic migraine and the drug has been recently approved in the US by the FDA, while it continues to be reviewed by other regulatory agencies. Herein we provide an in-depth review of its development. We start by summarizing its in vitro and in vivo pharmacology, and the phase I studies. We then review the late-stage clinical development, with a focus on its efficacy, safety, similarities, and uniqueness relative to other CGRP antibodies. We close by discussing lessons learned on the mechanisms of migraine and areas for future development and exploration.